Engineering Commons^™

Borophene And Graphene For Non-Enzymatic Biosensor- Ab-Initio Study, Omar A. Ismail

Theses and Dissertations

Non-enzymatic glucose sensing holds promise to overcome limitations associated with glucose oxidase, such as oxygen dependence and short shelf life. This study explores the potential sensing capabilities of borophene and graphene through direct interaction with various compounds, including β-glucose, uric acid, ascorbic acid, fructose, and acetaminophen. Using Density Functional Theory (DFT), we calculated binding energies and the respective Density of States (DOS) for these adsorbates on both graphene and borophene surfaces. Preliminary results suggest that borophene might exhibit nearly twice the affinity for β-glucose compared to graphene. Moreover, the calculated Density of States reveals distinct distortions in the electronic states …

Two-Dimensional Nanomaterials And Nanocomposites For Sensing, Separation, And Energy Applications, Md Ashiqur Rahman

Theses and Dissertations

Two-dimension (2D) nanomaterials have gained popularity for the last few decades due to their excellent mechanical, electrical and thermal properties. These unique properties of 2D nanomaterials can be exploited in various applications specially in sensor, energy, and separation devices. In this study, the sensing and energy generation performance of PVDF/PAni fiber mat systems made by the forcespinning method with and without graphene coating. The graphene-coated nanocomposites show an average output voltage of 75 mV (peak-to-peak) which is 300% higher compared to bare fiber mats and an output current of 24 mA (peak-to-peak) by gentle finger pressing. Moreover, the graphene-coated PVDF/PAni …

An Innovative Triboelectric Stent Sensor: Prospective Cardiovascular Health Monitor Device, Ulises Vidaurri Romero

Theses and Dissertations

Previous research that has focused on TENGs have lacked the proper application of this energy generator. Currently, heart disease remains the leading cause of death in the United States. With increasing demand for self-sustainable medical devices, this nitinol health monitor sensor device (NHMS) integrates the TENG applications with medical applications. The NHMS features memory shape nitinol electrodes that preserves the device structure while using PDMS and PVDF triboelectric effect to measure heart rate, blood pressure, and breathing patterns. Three constant pressures were measured in this study. At a constant pressure of stage 1, the NHMS produces an average AC of …

Characterization Of Fiber Bragg Grating Based, Geometry-Dependent, Magnetostrictive Composite Sensors, Edward Lynch

Theses and Dissertations

Optical sensors based on geometry dependent magnetostrictive composite, having potential applications in current sensing and magnetic field sensing are modeled and evaluated experimentally with an emphasis on their thermal immunity from thermal disturbances. Two sensor geometries composed of a fiber Bragg grating (FBG) embedded in a shaped Terfenol-D/epoxy composite material, which were previously prototyped and tested for magnetic field response, were investigated. When sensing magnetic fields or currents, the primary function of the magnetostrictive composite geometry is to modulate the magnetic flux such that a magnetostrictive strain gradient is induced on the embedded FBG. Simulations and thermal experiments reveal the …

Lead Free Piezoelectric And Triboelectric Energy Film For Energy Harvesting And Sensory Applications, Abu Musa Abdullah

Theses and Dissertations

In recent times, Triboelectricity and Piezoelectricity has been widely used for utilizing mechanical energy from ambient environment. Scientists are focusing towards developing advanced material composites for utilizing piezoelectricity and triboelectricity for energy harvesting and sensory applications. This work includes two projects regarding the application of lead free piezoelectric and triboelectric energy for energy harvesting and sensory applications. Human motion has been attributed as a source of mechanical energy to drive electronic devices and sensors through Triboelectric Nanogenerator (TENG). Based on the principles of single electrode TENG, we have developed a Triboelectricity based Stepping and Tapping Energy Case (TESTEC) which magnifies …

Developing And Comparing Sensor For Movement Analysis And Biofeedback, Umaiyaal Vasudevaraja

Theses and Dissertations

Background: Recent advances in the field of wearable technology are now at a peak in the sports field and the medical field. The validity, reliability, and application of such systems are still under research and yet to be revealed.

Purpose: This study aims to design and constructing the Inertial Measurement Unit (IMU) hardware with the required software to collect accelerometer data for potential use in human movement studies and test the efficacy of the collected IMU accelerometer data by comparing it with the motion capture data.

Methods: In this study, the IMU sensor is coupled with the Arduino, loaded with …

Low-Temperature Fabrication Process For Integrated High-Aspect Ratio Metal Oxide Nanostructure Semiconductor Gas Sensors, William Paul Clavijo

Theses and Dissertations

This work presents a new low-temperature fabrication process of metal oxide nanostructures that allows high-aspect ratio zinc oxide (ZnO) and titanium dioxide (TiO₂) nanowires and nanotubes to be readily integrated with microelectronic devices for sensor applications. This process relies on a new method of forming a close-packed array of self-assembled high-aspect-ratio nanopores in an anodized aluminum oxide (AAO) template in a thin (2.5 µm) aluminum film deposited on a silicon and lithium niobate substrate (LiNbO₃). This technique is in sharp contrast to traditional free-standing thick film methods and the use of an integrated thin aluminum film …

Microfluidic Devices And Biosensors, Long-Fang Tsai

Theses and Dissertations

My research broadly covers various important aspects of microfluidic devices and biosensors. Specifically, this dissertation reports: (1) a new and effective room temperature method of bonding polydimethylsiloxane (PDMS) microfluidics to substrates such as silicon and glass, (2) a new microfluidic pump concept and implementation specifically designed to repeatedly drive a small sample volume (<1 µL) very rapidly (~500 µL/min) through a sensor-containing flow channel to significantly decrease sensor response time through advection-driven rather than diffusion-driven mass transport, (3) use of a new microfluidic material based on polyethylene glycol diacrylate (PEGDA) to implement impedance-based dynamic nanochannel sensors for protein sensing, and (4) an investigation of galvanoluminescence and how to avoid it for conditions important to fluorescence-based dielectrophoresis (DEP) microfluidic biosensors. Over the last decade, the Nordin research group has developed a lab-on-a-chip (LOC) biosensor based on silicon photonic microcantilever arrays integrated with polydimethylsiloxane (PDMS) microfluidics for protein biomarker detection. Integration requires reliable bonding at room temperature with adequate bond strength between the PDMS element and microcantilever sensor substrate. The requirement for a room temperature process is particularly critical because microcantilevers must be individually functionalized with antibody-based receptor molecules prior to bonding and cannot withstand significant heating after functionalization. I developed a new room temperature bonding method using PDMS curing agent as an intermediate adhesive layer. Two curing agents (Sylgard 184 and 182) were compared, as well as an alternate UV curable adhesive (NOA 75). The bond strength of Sylgard 184 was found to be stronger than Sylgard 182 under the same curing conditions. Overnight room temperature curing with Sylgard 184 yields an average burst pressure of 433 kPa, which is more than adequate for many PDMS sensor devices. In contrast, UV curable epoxy required a 12 hour bake at 50 °C to achieve maximum bond strength, which resulted in a burst pressure of only 124 kPa. In many biosensing scenarios it is desirable to use a small sample volume (<1 µL) to detect small analyte concentrations in as short a time as possible. I report a new microfluidic pump to address this need, which we call a reflow pump. It is designed to rapidly pump a small sample volume back and forth in a flow channel. Ultimately, the flow channel would contain functionalized sensor surfaces. The rapid flow permits use of advection-driven mass transport to the sensor surfaces to dramatically reduce sensor response times compared to diffusion-based mass transport. Normally such rapid flow would have the effect of decreasing the fraction of analyte molecules in the volume that would see the sensor surfaces. By configuring the pump to reflow fluid back and forth in the flow channel, the analyte molecules in the small sample volume are used efficiently in that they have many opportunities to make it to the sensor surfaces. I describe a 3-layer PDMS reflow pump that pumps 300 nL of fluid at 500 µL/min for 15 psi actuation pressure, and demonstrate a new two-layer configuration that significantly simplifies pump fabrication. Impedance-based nanochannel sensors operate on the basis of capturing target molecules in nanochannels such that impedance through the nanochannels is increased. While simple in concept, the response time can be quite long (8~12 hours) because the achievable flow rate through a nanochannel is very limited. An approach to dramatically increase the flow rate is to form nanochannels only during impedance measurements, and otherwise have an array of nanotrenches on the surface of a conventional microfluidic flow channel where they are exposed to normal microfluidic flow rates. I have implemented such a dynamic nanochannel approach with a recently-developed microfluidic material based polyethylene glycol diacrylate (PEGDA). I present the design, fabrication, and testing of PEGDA dynamic nanochannel array sensors, and demonstrate an 11.2 % increase in nanochannel impedance when exposed to 7.2 µM bovine serum albumin (BSA) in phosphate buffered saline (PBS). Recently, LOC biosensors for cancer cell detection have been demonstrated based on a combination of dielectrophoresis (DEP) and fluorescence detection. For fluorescence detection it is critical to minimize other sources of light in the system. However, reported devices use a non-noble metal electrode, indium tin oxide (ITO), to take advantage of its optical transparency. Unfortunately, use of non-noble metal electrodes can result in galvanoluminescence (GL) in which the AC voltage applied to the electrodes to achieve DEP causes light emission, which can potentially confound the fluorescence measurement. I designed and fabricated two types of devices to examine and identify conditions that lead to GL. Based on my observations, I have developed a method to avoid GL that involves measuring the impedance spectrum of a DEP device and choosing an operating frequency in the resistive portion of the spectrum. I also measure the emission spectrum of twelve salt solutions, all of which exhibited broadband GL. Finally, I show that in addition to Au, Cr and Ni do not exhibit GL, are therefore potentially attractive as low cost DEP electrode materials.

Nanowire Zinc Oxide Mosfet Pressure Sensor, William Clavijo

Theses and Dissertations

Fabrication and characterization of a new kind of pressure sensor using self-assembly Zinc Oxide (ZnO) nanowires on top of the gate of a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) is presented. Self-assembly ZnO nanowires were fabricated with a diameter of 80 nm and 800 nm height (80:8 aspect ratio) on top of the gate of the MOSFET. The sensor showed a 110% response in the drain current due to pressure, even with the expected piezoresistive response of the silicon device removed from the measurement. The pressure sensor was fabricated through low temperature bottom up ultrahigh aspect ratio ZnO nanowire growth using anodic …

Multifunctional Orthogonally-Frequency-Coded Saw Strain Sensor, William Wilson

Theses and Dissertations

A multifunctional strain sensor based on Surface Acoustic Wave (SAW) Orthogonal Frequency Coding (OFC) technology on a Langasite substrate has been investigated. Second order transmission matrix models have been developed and verified. A new parameterizable library of SAW components was created to automate the layout process. Using these new tools, a SAW strain sensor with OFC reflectors was designed, fabricated and tested. The Langasite coefficients of velocity for strain (γS = 1.699) and Temperature (γT = 2.562) were experimentally determined. The strain and temperature characterization of this strain sensor, along with the coefficients of velocity, have been used to demonstrate …

Wireless Pressure Sensor System For Medical Applications, Xuehe Wang

Theses and Dissertations

Telemedicine in the modern era is a rapidly developing industry. In a telemedicine system, sensor is the key elements and play important role in any telemedicine applications, especially implantable sensors. Unlike traditional in vitro sensors, there are some special requirements for them like battery-less, compact, and bio-friendly. Therefore, many researchers in institutes as well as in industry are continually developing implantable sensor and sensor system to fulfill the requirements of medical applications.Nine in one thousand people in the United States are born with congenital heart defects and sixty percent die before one year old. As a result, it will be …

Nanocomposite High Displacement Strain Gauges For Use In Human-Machine Interfaces: Applications In Hand Pose Determination, Thomas B. Calkins

Theses and Dissertations

Conductive nanocomposites are finding many uses as multi-functional materials. One recent development involves the creation of high displacement strain gauges, which have potential applications in a variety of engineering roles. The piezoresistive nature of the gauges makes possible their strain sensing capability. The intent of this research is to show that specific High Displacement Strain Gauges can successfully be used in one human-machine interface application that will demonstrate their potential for a range of other human-machine interface applications. This will be shown in the development of these sensors to accomplish hand pose determination. The flexible and inexpensive gauges are attached …

Low Cost/ High Precision Flight Dynamics Estimation Using The Square-Root Unscented Kalman Filter, Trevor H. Paulsen

Theses and Dissertations

For over a decade, Brigham Young University's Microwave Earth Remote Sensing (MERS) team has been developing SAR systems and SAR processing algorithms. In order to create the most accurate image reconstruction algorithms, detailed aircraft motion data is essential. In 2008, the MERS team purchased a costly inertial measurement unit (IMU) coupled with a high precision global positioning system (GPS) from NovAtel, Inc. In order to lower the cost of obtaining detailed motion measurements, the MERS group decided to build a system that mimics the capability the NovAtel system as closely as possible for a much lower cost. As a first …

Piezoresistive Models For Polysilicon With Bending Or Torsional Loads, Gerrit T. Larsen

Theses and Dissertations

This thesis presents new models for determining piezoresistive response in long, thin polysilicon beams with either axial and bending moment inducing loads or torsional loads. Microelectromechanical (MEMS) test devices and calibration methods for finding the piezoresistive coefficients are also presented for both loading conditions. For axial and bending moment inducing loads, if the piezoresistive coefficients are known, the Improved Piezoresistive Flexure Model (IPFM) is used to find the new resistance of a beam under stress. The IPFM first discretizes the beam into small volumes represented by resistors. The stress that each of these volumes experiences is calculated, and the stress …

A Compliant Threshold Acceleration Sensor Integrated With Radio Frequency Identifiable Tags, Benjamin L. Todd

Theses and Dissertations

Fully compliant bistable mechanisms have been proposed to be used as threshold accelerometers. The advantages to using these devices are that they require no external power to operate and maintain their sensing state. Using this characteristic the devices can be integrated with passive radio frequency identification tags (RFID). This allows for the sensing package to lay dormant with no maintenance needed until the sensor is read by the RFID reader. This thesis presents a successfully fabricated and integrated threshold accelerometer with a passive RFID tag. This in turn has been successfully read with an RFID reader and shown to act …

Design Of Piezoresistive Mems Force And Displacement Sensors, Tyler Lane Waterfall

Theses and Dissertations

MEMS (MicroElectroMechanical Systems) sensors are used in acceleration, flow, pressure and force sensing applications on the micro and macro levels. Much research has focused on improving sensor precision, range, reliability, and ease of manufacture and operation. One exciting possibility for improving the capability of micro sensors lies in exploiting the piezoresistive properties of silicon, the material of choice in many MEMS fabrication processes. Piezoresistivity—the change of electrical resistance due to an applied strain—is a valuable material property of silicon due to its potential for high signal output and on-chip and feedback-control possibilities. However, successful design of piezoresistive micro sensors requires …

Solid-State Impact-Ionization Multiplier, Hong-Wei Lee

Theses and Dissertations

This dissertation presents an innovative solid-state current amplifier based on impact-ionization. Unlike avalanche photodetectors which use the same amplification principle, this device can be integrated with any external current source. A discrete amplifier was built on a silicon surface using standard CMOS fabrication processes including lithography, oxidation, ion implantation, diffusion, chemical wet etching, metal deposition, annealing, and rapid thermal processing. Testing was performed by connecting the device to a silicon photodiode, indium-gallium-arsenide photodiodes, and a function generator to demonstrate its compatibility with arbitrary current sources. Current gains above 100 along with pre-amplified leakage currents of less than 10 nA were …

A Framework For An Implantable Wireless Pressure And Volume Sensor Focusing On The Diagnosis And Treatment Of Shunt Failure In Hydrocephalus Patients, Donald Monte Wichern

Theses and Dissertations

The framework for a permanently implantable wireless compliance sensor was developed and validated using laboratory experiments. The proposed sensor would measure the intracranial pressure and fluid volume in the brain and return this information to a monitoring device. The designed sensor received power remotely from the monitoring device negating the need for an implanted power source. Impedance measurement estimation techniques were suggested, studied and applied to the compliance sensing system. A new impedance measurement technique, accounting for multiple variability in the domain, was developed. An extensive simulation environment was designed and used to develop the laboratory experiments and hardware. The …

Polarimetric Temperature Sensor Using Core-Replaced Fiber, Benjamin L. Ipson

Theses and Dissertations

Optical fibers are increasingly being used to create sensing devices. The D-fiber has an elliptical core and exhibits birefringence. This birefringence can be used to create a polarimetric sensor. The elliptical core supports two orthogonal modes that have separate effective indices of refraction. The indices of refraction change with a change in temperature. Since the effective indices of refraction change differently for the two modes, the birefringence also changes. This change in birefringence can be seen as a change in detected power through the fiber through the use of polarizers. The fiber then becomes a temperature sensor. The sensitivity of …